There is provided a control method of a flow regulating valve of an oxidizing gas in a fuel cell. In a load disconnected state that the fuel cell is electrically disconnected from a load, the control method gradually opens the flow regulating valve that is configured to supply the oxidizing gas to a cathode of the fuel cell by a predetermined valve opening each time from a full-close position or gradually closes the flow regulating valve by a predetermined valve opening each time from a full-open position, so as to gradually change a supply amount of the oxidizing gas introduced to the cathode and cause hydrogen transmitted from an anode to the cathode in the fuel cell to be oxidized. The control method measures an open circuit voltage of the fuel cell accompanied with oxidation of the hydrogen and stores at least one valve-opening position among valve-opening positions of the flow regulating valve at a predetermined number of timings including a timing when the measured voltage shifts to an increase or shifts to a decrease, as a regulation reference valve-opening timing.

A power supply system includes a fuel cell, a power storage device, a first voltage adjusting device, a second voltage adjusting device, and a controller. The controller is to control the first voltage adjusting device and the second voltage adjusting device. The controller is to switch the second voltage adjusting device from a direct coupling state to a voltage adjusting state in a case where a first absolute value of a first difference between a secondary voltage of the second voltage adjusting device applied across a load and a fuel cell voltage is less than a predetermined allowable voltage value or in a case where a second absolute value of a second difference between a fuel cell current being to flow from the fuel cell into the first voltage adjusting device and a target current value of the fuel cell current exceeds a predetermined allowable current value.

A fuel cell system performs a first control of stopping power generation of a fuel cell stack by closing a supply-side stop valve during power generation of the fuel cell stack, and a second control of driving an air pump by using surplus power generated in a moving body to thereby discard the surplus power. If a closed state of the supply-side stop valve is detected when the first control and the second control start to be executed, the air pump is driven in a predetermined state.

A method and apparatus for operating an intermediate-temperature solid-oxide fuel cell stack (10) with a mixed ionic/electronic conducting electrolyte in order to increase its efficiency. The required power output of the solid-oxide fuel cell stack (10) is determined and one or more operating conditions of the solid fuel cell stack (10) are controlled dependent upon the determined required power output. The operating conditions that are controlled may be at least one or the temperature of the fuel cell stack and the dilution of fuel delivered to the fuel cell stack.

An apparatus and a method for controlling a fuel cell stack are provided to improve the performance (output) of the fuel cell stack that has suffered from deterioration. The performance is improved by adjusting a stoichiometric ratio (SR) of air supplied to the fuel cell stack and an operating temperature of the fuel cell stack based on the basis of an open-circuit decay time (ODT) indicating a time taken for a cell voltage to be reduced from a reference voltage to a threshold voltage when the supply of air to the fuel cell stack is cut off.

A fuel cell system of the present invention can suppress an excessively wet or dry state of a fuel cell stack so as to thereby ensure the durability of the fuel cell stack. The fuel cell system supplies an oxidant gas with a reduced flow rate per unit time and for a long time period if the rate of voltage decrease of the stack becomes faster than a threshold rate, and supplies the oxidant gas with an increased flow rate per unit time and for a short time period if the rate of voltage decrease becomes slower than a threshold rate.

A method for controlling startup of a fuel cell vehicle is provided. The method includes starting to adjust supply of hydrogen and air to a fuel cell and setting a control voltage of a side of a main bus end of a converter disposed between the main bus end and a high-voltage battery to a predetermined lowest control voltage. An output voltage of the side of the main bus end of the fuel cell and the control voltage of the side of the main bus end of the converter are then compared to adjust an amount of air supply to the fuel cell based on the comparison.

A method of determining hydrogen deficiency of a fuel cell having a plurality of cell groups includes a reference value storage step of storing, as a reference value, a value of impedance in a state where hydrogen-off gas is discharged from the fuel cell and hydrogen gas and oxidant gas are supplied, a measured value calculation step of calculating a measured value of impedance based on a voltage of the cell groups and a current of the fuel cell, a corrected value calculation step of calculating a corrected value of impedance by correcting the measured value based on the reference value, and a determination step of determining that hydrogen deficiency occurs in a case where the corrected value exceeds a predetermined threshold.

A fuel cell system according to the present invention comprises: a fuel cell including a membrane-electrode assembly in which electrodes, each having a catalyst layer, are arranged on both surfaces of a polymer electrolyte membrane; and a control apparatus that performs performance recovery processing for the catalyst layer by decreasing an output voltage of the fuel cell to a predetermined voltage, wherein the control apparatus predicts a timing of an output increase request being made to the fuel cell and determines the necessity and content of the performance recovery processing based on a result of the prediction.

This fuel cell stack activation method is a method for activating a fuel cell stack provided with a solid polymer-containing electrolyte membrane, an anode electrode, and a cathode electrode, the method comprising: a first current application step for applying a current by electrically connecting the two electrodes via an external electrical load in a state in which a potential difference is generated between the two electrodes by supplying air as a cathode-side gas to the cathode electrode while supplying hydrogen gas as an anode-side gas to the anode electrode; and a second current application step for applying a current by electrically connecting the two electrodes via an external electrical load in a state in which a potential difference is generated between the two electrodes by supplying nitrogen gas as a cathode-side gas to die cathode electrode while supplying hydrogen gas as an anode-side gas to the anode electrode.